Despite the majority of existing works, e.g., [1]}, [2]}, which assumed independent Rayleigh model, we consider the practical effect of spatial correlation, which is unavoidable in realistic IRS-assisted systems [3]}.Contrary to most works on IRS that model correlation by using models for conventional antenna arrays, we adopt the recently presented correlation model by the authors in [3]}, being more suitable for IRS. Also, according to the JSDM method, despite that the individual effects are different across different UEs, the covariances matrices, describing the aggregate result of path-loss and correlation, have been assumed equal across different UEs of the same group since they are clustered accordingly. Thus, \( {\mathbf {h}}_{\mathrm {d},g_{k}} \)  and \( {\mathbf {h}}_{2,g_{k}} \) , concerning UE \( k \)  in group \( g \) , are expressed as
\({\mathbf {h}}_{\mathrm {d},g_{k}}&={\mathbf {R}}_{\mathrm {BS},g}^{1/2}{\mathbf {z}}_{\mathrm {d},g_{k}},~{\mathbf {h}}_{2,g_{k}}={\mathbf {R}}_{\mathrm {IRS},g}^{1/2}{\mathbf {z}}_{2,g_{k}},\) 
